Treatment of mineral oils by heat



Aug. 7, 1934. w. J. PERI-:LIS

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TREATMENT OF MINERAL OILS BY HEAT Original Filed Sept. 23, 1926 2 Sheets-Sheet 2 .IPM/ENTE by c, vo

ATTRNE lPatented Aug. 7, 1934 PATENT lol-"FICE TREATMENT `or MINERAL olLs BY HEAT Walter James Perelis, Boston, Mass., assignor, by mesne assignments, to Universal Oil Products Company, Chicago, Ill., a corporation of South Dakota Application September 23, 1926, Serial No. 137,344 Renewed January 4, 1934 Claims. (Cl. 196-58) This invention relates to improvements on processes dealing with cracking of mineral oils by heat.

I have experienced that agitation in one of its forms is essential when heating up hydrocarbon materials. In this w ay higher temperatures can be reached, lwithout the danger of coking. The reason for this fact is the bad heat conductance of the oil, which does not allow a uniform heating up through the cross section, without agitation.

Such agitation can be produced either with the help of mechanical agitation or more simply and just as effectively with the help of turbulence in a tubular heater.

In the heating up period there is usually no gasoline present, therefore I put somewhat heavier hydrocarbons into the vapor phase to create the turbulence. Therefore comparatively lower pressures have to be used in the heating up period, if turbulence has to be created in a tubular heater. Pressures of the order of 200 pounds per square inch are suitable for such heating up.

2 After the material has been `heated up to an effective cracking temperature, time on cracking temperature has to be given to it if big conversions are expected.

In this period pressures around 200 pounds per square inch are not high enough for maximum results. I have found it therefore advantageous to heat up the material under pressures of the order of 200 pounds per square inch and to increase the pressure of the fiow after such heating up period.. Such pressure increase is done with the help of a pump.

While I am agitating the material I heat it under pressure under flow to a maximum temperature.

If it should be attempted to pass into a tank shaped container oil on maximum cracking temperature to give the material time on cracking temperature during its passage through said container, a large amount of coke would be produced; but if the material is passed through a tubular apparatus in which it is turbulently owing or if it is effectively agitated in a tank shaped container the coke formation will be practically eliminated.

To illustrate the above mentioned statement I am describing the result' of my experiments. I have used Luling crude oil in two cases.

In one instance I have heated the oil under flow under pressure in a tubular heater to 860 F., then passed it through a heat insulated chamber 6'x40. In twenty hours I have lled up the tank with coke.

In the other case after heating up the material in the tubular heater to 890 F., it entered a tubular apparatus and was kept there under flow at a temperature around 890 F. while agitated with the help of turbulence; no appreciable amount of coke accumulated after two weeks of continuous operation.

For several years I have compared the quantities of coke produced per barrel of gasoline, in large scale refinery operation, in apparatuses using tanks, to give time for the material on cracking temperatures, with the quantities of coke produced in apparatus using tubular equipmentor tanks equipped with efficient mechanical agitator and I find that I produced for oils like Luling crude oil 15 pounds coke per barrel of gasoline in tank shaped apparatus without mechanical agitator against one pound of coke in apparatuses where the material has been thoroughly agitated during the time on cracking temperatures. (In tubular apparatus the agitation is done with the help of turbulence.)

I have to remark that the rapid coke formation can be eliminated when using tanks without agitation if the entering temperature is kept vlow enough, which means conversion reduction.

To avoid such a loss the material should be heated up under pressure under flow through a tubular heater to a maximum temperature but after that before entering the tank Without agi-l tation it should pass first through an apparatus (insulated, tubular or tank with an agitator) and kept there in violent motion on cracking temperature until it loses some of its heat, while forming gasoline, until it reaches such a comparatively low temperature, which, though suitable for cracking conversions, does not result in coke formation when the material passes in the next step through va tank shaped apparatus which is not equipped with an agitator.

There are other means to reduce the coke production in apparatus using a tank shaped vessel to give time for the material on cracking temperature. 1

The material can be heated up under iiow under high pressures to an eiective cracking temperature, then the pressure can be partially reduced before entering the tank. In such a case the pressure reduction will cause a temperature reduction which is effective to reduce the coke formation; of course the temperature will be high enough yet for cracking conversions.

Another way to eliminate the coke accumulavunder ow in a tubular heater, increase the pressure, continuing the flow through'tubular heaters, decrease first the temperature for a period, then increase the temperature, reduce the temperature within the cracking range in a tubular apparatus, pass' the material into a tank shaped apparatus, carry the material through the same while on effective cracking temperature, reduce the temperature to around 700 F. and relieve the pressure, allowing vaporization.

The described means are effective to produce with the help of heat y.a maximum amount of gasoline from heavier oils in different types of apparatus, eliminating at the same time the production of the huge amount of coke, which burdens the rener) using well introduced'cracking vproces/ses today;l upsettingy at the same time the theory that the coke formation in cracking processes is a natural consequence of the gasoline production, because my process produces increased amount of gasoline, nevertheless eliminates practically the coke formation. 1t leads me to believe that the major part of the coke produced by well known cracking processes is not the consequence of the cracking proper, but the result of vaporization, which is not controlled.

The preferred form of apparatus is illustrated in diagram in Fig. l of the accompanying drawings.

Fig. 2 is a diagram with curves showing kthe approximate temperatures and approximate pressure conditions when treating crude oils in the preferred form of apparatus. w

Fig. 3 is a diagram of' a modified form of apparatus having drums provided with mechanical agtators. c

The raw material is yforced by pumpr 21 through a gasoline vapor heat exchanger 20, through line,38 to the top of vapor heat exchanger 16. In the said heat exchanger it meets the vapors 'released in vaporizer 14 coming through line 15;` The result of this contact will be a separation of the light `fractions of the raw materialgtogether with the light fractions of the cracked eiiiux, in Vapor form, from a liquid consisting of the heavy fractions of the raw material together with the heavy fractions of the vapors of the cooled cracked elux.

The liquid runs through pipe 39 into container 33 from Where it leaves through line 1 and is pulled by the pump 2,'which discharges it through heat exchanger 4, line 5 and heater 6l, in `which the material is heated up to an efficient cracking temperature while under pressures of the order of 200 pounds per square inch. With the help of pump43 the pressure is increased and the material is moved through coil 71, in which the temperature is `decreasing Within the cracking range, ,then it movesk through heater 81 where the temperature is increased, then it con'- tinues to ow through line 8, throughtubular apparatus 10, through tank shaped container 11, through line 12, heat exchanger 4 and pressure -iow enters the tank 1l.

release-valvel40 before it travels through line 13 to the vaporizer 14. Here the material is agitated with steam admitted through pipe 41` and spray pipe 42. A liquid which is fuel oil will separate out from vapors which enter the vapor.l heat exchanger 16 through line 15.

As before mentioned the temperature of the` fmaterial decreases in 71; it increases again in p 81 to the maximum. After this, instead of cooling down suddenly the material which is at yeffective cracking temperature, it is protected against outside heat losses. then continue to produce gasoline for a substantial time While its temperature is decreasing. (A part of the sensible heat is consumed for the chemical reaction.)

The material will The material leaving heater 81 passes rst through a tubular apparatus 10 and then through a tank shaped container 11. If apparatus 10 should be left out, too much coke f would accumulate in kr11," but if the material is cooled in 10, while producing gasoline, to the order of 830 F. thecoke formation will be elim. inated later in 11. Preferably a valve 45 is provided in the line between Ithe tubular member 10 and tank 11 to permit pressure reduction before entering the tank as hereinbefore mentioned.

The vapors of the cooled cracked eiilux contact in 16 with the raw material.l Th'e result of this contact is a v aporous'and a liquid fraction. The

liquid fraction is accumulating in 33 and is handled as previously described. The vaporous fractions leave through 17 and enter the recti-r` Iier 18. Rectifier l`8 is sprayed from the top with gasoline passing through the valve 22 and is heaad onthe bottom, using the reboiler arrangement 30, 29, A28; a partbf the material accumulating at the bottom of 18 is taken by the pump 30 and is discharged through the reboiler 29, where it is heated, back through 28 to the bottom of the tower. g

The tower 18 will separate a vaporous fraction (gasolinel. from ,a liquid (kerosene and light` gasoil). The gasoline passes through line 19, heat exchanger 20, valve 23, line 24, water cooler 25, line 26 to a storage tank 27.

" The kerosene and light gasoil pass through valve 31 or through valve 32. If they go through valve 31, then they pass through watercooler 34 and are accumulated in the storage tank 35. If I` keep valve 3l closed, but open valve 32 the kerosene and light gasoil fractions can be mixed with the heavier oils in 33 and recracked.

The produced sediment free fuel oil leaves the vaporizer 14, is cooled in water cooler 36 and is accumulated in tank 37. Coils 6l, 8l, 29 are built in a furnace as Shown respectively at 6, 9 and 44. The parts 4, 71, 10, 11, 14, 16, 33, 18, 20 are heat insulated. Y

When.V the processv is practiced ashereinbefore described by heating the material under flow and under high pressures to cracking temperature and then partially reducing the pressure by means of valve 45, a pressure reduction of from 50 to 200 pounds is desirable before the Such a pressure reductionv causes the temperature to be reduced sufficiently. for the desired reduction of coke formation in the tank l1. 'I'he pressure is further reduced after the oil stream leaves the tank 11 to support the vaporization in vaporizer 14. The vaporization is usually carried out at pressures close to atmospheric pressure in the vaporizer 14..

Referring to the modified form shown in Fig. 3, there are provided drums 61a, 71, 81a, 10"', ln place of the tubular coils 61, 71, 81 and 10, respectively, shown in Fig. 1, each of said drums being provided with mechanical agitators. The drum 61a is provided with rotary agitator shafts a and a' having agitator blades mounted thereon, the shaft a having a pulley 46 connected with any suitable driving mechanism, not shown, said shaft a having driving connection with the shaft a'.

The drum '71a is provided with rotary agitator shafts a2, a3, each equipped with agitator blades, said shafts having driving connection with each other, the lshafts a2 having mounted thereon a pulley 46' connected with any suitable driving mechanism, not shown.

The drum 81a is provided With rotary agitator shafts a4, a5, each equipped with agitator blades and having driving connection with each other, the shaft a4 having a pulley 462 which may be driven by any suitable means, not shown.

'I'he drum 10a is equipped with rotary agitator shafts a6, a", each provided With agitator blades and having driving connection with each other, the shafts a6, al having a pulley 463 driven by any suitable means, not shown. v

The drums 61 and 81a are heated by the furnaces oa and 98L respectively.

The pipe 5 leads from the heat exchanger 4 to the drum 61a. The oil passes from the drum 61a to the drum 715 through pipe 61b and the oil from drum 'Ila passes to the drum 81a through pipe '71". From drum 81 it passes through pipe 891 to drum 10 and from drum 10a it passes through pipe 10b to tank 11a.

Located in pipe 10b is a valve 45 whereby the pressure' may be reduced before entering the tank 11a as hereinbefore mentioned.

Preferably the drums 7l, 10a and 113 are insulated against loss of heat.

'Ihe structure shown in Figure 3 as described is to replace the coils 61, '71, 81, -10 and the tank 11 in Figure i and is to be connected with the heat exchanger 4 and the tank 14 and the other apparatuses` associated with the apparatus containing the agitation means with the device illustrated and described in Figure l.

What I claim is:

1. Process for cracking mineral oils by heat characterized by subjecting a liquid stream of oil while under turbulent ow in a tubular heater under pressure to a cracking temperature and then to increase of temperature in succession, the temperature of the flowing stream remaining within the cracking range, while the pressure is decreasing, increasing and decreasing in succession.

2. Process for the treatment of mineral oils by heat comprising heating up the material under flow to a cracking temperature in the liquid-vapor phase under pressure, keeping the material in the cracking range for a substantial time, increasing the pressure after said heating up, reducing the temperature Within the cracking range in a tubular apparatus under turbulent flow, further decreasing the temperature within the cracking range without turbulent now, then reducing the temperature below the eiective cracking range, then reducing the pres sure to practically atmospheric pressure.

3. Process for the treatment of mineral oils lby heat comprising heating up the material under flow to a cracking temperature in the liquid-vapor phase under pressure, keeping the material in the cracking range for a substantial time, increasing the pressure after said heating up, reducing the temperature within the cracking range while agitating, further reducing the temperature below the eiective cracking range, then reducing the pressure.

4. Process for the treatment of mineral oils by heat comprising heating up the material under ow to a cracking temperature inA the liquid-vapor phase under pressure, keeping the material in the cracking range for a substantial time, increasing the pressure after said heating up, reducing the temperature of the material Within the cracking range While agitating, further decreasing the temperature within the cracking range Without agitation, then reducing the temperature below the cracking range, then reducing the pressure.

5. Process for the treatment of mineral oils by heat comprising heating up the material under flow to a cracking temperature in the liquid-vapor phase under pressure, keeping the material in the cracking range for a substantial time, increasing the pressure after 'said heating up, reducing the temperature within the cracking range in a tubular zone under turbulent ow, further reducing the temperature below the cracking range, then reducing the pressure to practically atmospheric pressure.

WALTER JAMIES PERELIS. 

